----------------------
- BUILD INSTRUCTIONS -
----------------------

Step 0: Build and install llvm
------------------------------

I'm assuming anyone reading this knows how to build and install llvm.
You need the latest llvm from the subversion repository.

Step 1: Build gcc
-----------------

Check out gcc from the gcc subversion repository:
  svn checkout svn://gcc.gnu.org/svn/gcc/trunk SomeLocalDir
Apply the patches in the gcc-patches subdirectory, if any.  Hopefully one day
the plugin will work with an unpatched gcc, but for the moment a few small
patches need to be applied.  Configure gcc with your favorite options.
Build gcc, and install it somewhere.

Step 2: Build the plugin
------------------------

In the Makefile, set the GCCSOURCE_DIR variable to point to the place you
checked out the gcc repository, rather than to where I checked it out.
Set the GCCOBJECT_DIR to point to the place you built the repository.
Admire the awfulness of the build system, and make a mental note to rewrite
it properly.

Build the plugin using "make".  The end result of the build is a shared
library, llvm.so.

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- USAGE INSTRUCTIONS -
----------------------

Run gcc as usual, but pass -fplugin=./llvm.so as an extra command line argument.
Make sure you use the gcc you installed above, not the system gcc!

Currently the plugin isn't capable of compiling much - you have been warned.

The plugin accepts a few command line arguments, for example
-fplugin-arg-llvm-enable-gcc-optzns
Search for the comment "Process any plugin arguments" in llvm-backend.cpp,
the argument parsing code is just after this.